Intrinsic resistivity changes associated with charge density wave (CDW) phase transitions in 1$T$-TaS$_2$ hold promise for non-volatile memory and computing devices based on the principle of phase change memory. Intermediate resistance states, which offer distinctive opportunities for neuromorphic computing, have been observed in 1$T$-TaS$_2$ but the metastability responsible for this behavior makes the nature of multistate switching unpredictable. Here, we demonstrate the synthesis of nanothick verti-lateral 1$H$-TaS$_2$/1$T$-TaS$_2$ heterostructures in which the number of endotaxial metallic 1$H$-TaS$_2$ monolayers dictates the number of high-temperature resistance transitions in 1$T$-TaS$_2$ lamellae. Further, we also observe heterochirality in the CDW superlattice structure, which is also modulated in concert with the resistivity steps. This thermally-induced polytype conversion nucleates at folds and kinks where interlayer translations that relax local strain favorably align 1$H$ and 1$T$ layers. This work positions endotaxial TaS2 heterostructures as prime candidates for non-volatile device schemes implementing coupled switching of structure, chirality, and resistance.
Published in: "arXiv Material Science".